MATERIAL HANDLING—TRANSPORTATION OF SOLIDS 103 while Formula (23) is a general equation by which the carrying capacity of any standard size of bucket carrier in tons per hour may be calculated for materials of known weight. TABLE 13.—CAPACITY OF BUCKET CAERIEES IN TONS PER HOUR Material weighing 100 Ib. per cubic foot. Carrier speed 50 ft. per minute Bucket length by width, inches Spacing of buckets 18 in. 24 in. 30 in. 36 in. Tons per hour 12 by 12 16 by 12 16 by 15 18 by 15 20 by 15 24 by 15 20 by 20 24 by 20 30 by 20 36 by 20 30 by 24 36 by 24 25.76 34.24 53.60 60.15 19,36 25.68 40.20 45.10 52.40 60.10 88.80 106.70 15.41 20.55 32.15 36.10 41.90 48.00 71.00 85.40 106.70 128.00 12.84 17.12 26.80 30.07 33.45 39 . 60 ' 59.30 70.40 89.10 106.70 124.60 153.72 w = Where, 100,000 S Formula (23) W = Capacity in tons per hour, w — Width of bucket in inches equals depth of bucket, I = Length of bucket in inches, V = Speed of carrier in feet per minute, S = Spacing of buckets in inches, and w' = Weight of material handled in pounds per cubic foot. Bucket carriers, like bucket elevators, are balanced when not loaded, but the calculation of power requirements is complicated by the question of method of conveying the load over horizontal stretches—whether the load is scraped along by rigid buckets or whether the load is carried in buckets running on rollers supported on guide rails. The saving in power on horizontal runs by the pivoted-bucket construction is sacrificed to some extent by the necessity of loading the individual buckets by reciprocating feeders—consuming power—in order to avoid spill of material. Formula (24) is a convenient equation for ascertaining power requirements for either type of carrier, the constants caring for the difference in requirements. (AL+J&HW §W 100,000" +100 Horsepower = ——^ Formula (24) Where, A — Constant = 28 for carriers with pivoted buckets, = 103 for carriers with rigid buckets, B = Constant = 108 for carriers with pivoted buckets, = 133 for carriers with rigid buckets, L = Total horizontal span of carrier in feet, H = Total lift of carrier in feet, and W = Load handled in tons per hour.